Gamma Matching Question
 

I am planning to build a magnetic loop antenna and
feed it by means of a gamma match. I understand
that a gamma match will work over a wide range of
frequencies. I hope to work a number of bands using
the same loop.

My question is -- when I'm ready to test the antenna
do I adjust the gamma match at the lowest frequency I
plan to use, or the highest?

I have considered other forms of coupling the
rig to the transmitter but prefer to use the gamma
match.

Thanks in advance for any assistance or advice in this
matter.

Irv VE6BP

Gamma Matching Question
 

Irv Finkleman wrote:
I am planning to build a magnetic loop antenna and
feed it by means of a gamma match. I understand
that a gamma match will work over a wide range of
frequencies. I hope to work a number of bands using
the same loop.

The gamma match principle will work over a wide range of frequencies
but a given gamma match is rather narrow banded.

Unless your gamma match is really mechanically clever like perhaps the
SteppIR antennas, it isn't going to cover multiple bands.

Some references for study:

http://www.bcpink.com/KB3IFH/files/D...%20article.pdf

http://www.k1ttt.net/technote/gamma.html



--
Jim Pennino

Gamma Matching Question
 

On Sat, 21 Sep 2013 11:50:40 -0600, Irv Finkleman wrote:
I am planning to build a magnetic loop antenna and
feed it by means of a gamma match.

I understand
that a gamma match will work over a wide range of
frequencies.

Your understanding is in error.
At best a gamma match will "work well" over a 1-2% freq. range --
for selected definitions of "work well.

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
38.24N 104.55W | @ config.com | Jonesy | OS/2
* Killfiling google & XXXXbanter.com: jonz.net/ng.htm

Gamma Matching Question
 

Thanks to Jim and Jonesy -- I'm not very familiar with
all the ins and outs of Gamma matching, but in a number of
cases of Magnetic Loops where the loop covers a number
of bands e.g. 80-15m, 80-30M, the builders used a
Gamma match which when set needs no adjustment between
bands. Perhaps the Magnetic Loop has different properties,
although the authors of the articles claimed the matching
portion was a 'form of Gamma Match' and in one case
referred to the matching portion as a form of autotransformer
which I interpret to mean a non-circular feed loop of sorts.

In one loop design by Peter Parker VK3YE whose loop
covers 160-15 meters, the author advised me (when I
queried the Gamma question to him) that the
gamma when set as designed serves all bands well.
In other designs the gamma match or whatever it
might be, seems to work and did not seem to be a
problem or I think it might have been commented
on by the authors.

I will be investigating all these things soon -- I have just
recovered over a few years of some pretty heavy
abdominal surgeries and will be moving to a senior's
residence where I will have a balcony to work from.
It will be nice to get back on the air again after having
had to sell my house after the first surgery where I
had room for all different forms of antennas. Now I will
be back on the air again but will have to work under
certain restrictions such as no wires to nearby trees and
so forth. A magnetic loop or some form of windowsill
antenna will likely be my best bets. I'm looking forward to
the experience! I've always maintained to other old timers
who moved into condos where there restrictions that there
would always be some way to get on the air -- now I'm going
to have to walk the talk myself! One way or another I'm
not going to give up 55 years of hamming -- even if I can
only work across town! I'm shooting for multiband 80-10M
operation -- or bust! (Touch wood!)

Thanks,

Irv VE6BP
..
"Allodoxaphobia" wrote in message
t...
On Sat, 21 Sep 2013 11:50:40 -0600, Irv Finkleman wrote:
I am planning to build a magnetic loop antenna and
feed it by means of a gamma match.

I understand
that a gamma match will work over a wide range of
frequencies.

Your understanding is in error.
At best a gamma match will "work well" over a 1-2% freq. range --
for selected definitions of "work well.

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
38.24N 104.55W | @ config.com | Jonesy | OS/2
* Killfiling google & XXXXbanter.com: jonz.net/ng.htm

Gamma Matching Question
 

Irv Finkleman wrote:
Thanks to Jim and Jonesy -- I'm not very familiar with
all the ins and outs of Gamma matching, but in a number of
cases of Magnetic Loops where the loop covers a number
of bands e.g. 80-15m, 80-30M, the builders used a
Gamma match which when set needs no adjustment between
bands. Perhaps the Magnetic Loop has different properties,
although the authors of the articles claimed the matching
portion was a 'form of Gamma Match' and in one case
referred to the matching portion as a form of autotransformer
which I interpret to mean a non-circular feed loop of sorts.

In one loop design by Peter Parker VK3YE whose loop
covers 160-15 meters, the author advised me (when I
queried the Gamma question to him) that the
gamma when set as designed serves all bands well.
In other designs the gamma match or whatever it
might be, seems to work and did not seem to be a
problem or I think it might have been commented
on by the authors.

I will be investigating all these things soon -- I have just
recovered over a few years of some pretty heavy
abdominal surgeries and will be moving to a senior's
residence where I will have a balcony to work from.
It will be nice to get back on the air again after having
had to sell my house after the first surgery where I
had room for all different forms of antennas. Now I will
be back on the air again but will have to work under
certain restrictions such as no wires to nearby trees and
so forth. A magnetic loop or some form of windowsill
antenna will likely be my best bets. I'm looking forward to
the experience! I've always maintained to other old timers
who moved into condos where there restrictions that there
would always be some way to get on the air -- now I'm going
to have to walk the talk myself! One way or another I'm
not going to give up 55 years of hamming -- even if I can
only work across town! I'm shooting for multiband 80-10M
operation -- or bust! (Touch wood!)

Thanks,

Irv VE6BP

The easiest way to achieve that is get yourself one of the autotunners
which will tune just about anything.

The high power ones tend to be expensive but if you are running the typical
rig barefoot in the 100 watt range they are not that expensive these days.

I have a vertical with an autotunner that covers all bands from 80 to 10,
including of course 30, 17, and 12.

I contemplated using a loop instead of a vertical but the vertical was
easier to put up where I live.


--
Jim Pennino

Gamma Matching Question
 

In article ,
"Irv Finkleman" wrote:

will be moving to a senior's
residence where I will have a balcony to work from.

Irv-

Go ahead and try the loop. At least you will be on the air, and you may
be surprised how well it works.

I once lived in an apartment where a previous resident had installed a
trucker's mirror antenna mount on the metal balcony rail. I used it
with mobile whips to get on HF. The metal rail worked as a ground
plane, and my TS-690S built-in tuner was able to match it.

You might also consider dipoles made from mobile whips. I have had good
luck, especially on higher bands. I currently have an "Octopus" antenna
made from four sets of mobile whips fed in parallel. It might not fit
on your balcony, but fits inside my attic. (The Octopus was published
in the December, 2007, issue of QST.)

73,
Fred
K4DII

Gamma Matching Question
 

OOps! I sent replies direct to Fred instead of the newsgroup!
Here's a repeat of one!
------------------

Thanks Fred. I am determined to experiment with the Magnetic Loop
only because I haven't worked with one before. I am also keeping
in mind a windowsill antenna as a backup, and also in case I run into
problems getting the Loop going.

I've previously worked the gamut of antennas from the old 'Gotham
Vertical' which was a classic back in the fifties, through all kinds
of dipoles, towers beams and rotors, random wires, folded Marconis,
and such but never a loop.

The Magnetic Loop is a fairly new concept that intrigues me, and
unlike a mobile whip or other compromise antenna, it is 'complete'
in itself and a lot of guys are giving it pretty good reports. As well,
it will serve on a balcony without being overrly obtrusive.

Time will tell but I'm going to have some fun!

I'll have to look for the Octopus in the QST Archives, not
to build one but to have a look at it.

Tks agn es 73

Irv VE6BP.

"Fred McKenzie" wrote in message
...
In article ,
"Irv Finkleman" wrote:

will be moving to a senior's
residence where I will have a balcony to work from.

Irv-

Go ahead and try the loop. At least you will be on the air, and you may
be surprised how well it works.

I once lived in an apartment where a previous resident had installed a
trucker's mirror antenna mount on the metal balcony rail. I used it
with mobile whips to get on HF. The metal rail worked as a ground
plane, and my TS-690S built-in tuner was able to match it.

You might also consider dipoles made from mobile whips. I have had good
luck, especially on higher bands. I currently have an "Octopus" antenna
made from four sets of mobile whips fed in parallel. It might not fit
on your balcony, but fits inside my attic. (The Octopus was published
in the December, 2007, issue of QST.)

73,
Fred
K4DII

Gamma Matching Question
 

On 9/21/2013 12:50 PM, Irv Finkleman wrote:
I am planning to build a magnetic loop antenna and
feed it by means of a gamma match. I understand
that a gamma match will work over a wide range of
frequencies. I hope to work a number of bands using
the same loop.

My question is -- when I'm ready to test the antenna
do I adjust the gamma match at the lowest frequency I
plan to use, or the highest?

I have considered other forms of coupling the
rig to the transmitter but prefer to use the gamma
match.

Thanks in advance for any assistance or advice in this
matter.

Irv VE6BP




I gave up the idea of a magnetic antenna when I found how much the
tunable capacitor cost when using 1500 watts. Ouch

Gamma Matching Question
 

"Irv Finkleman" wrote in message
...
I am planning to build a magnetic loop antenna and
feed it by means of a gamma match. I understand
that a gamma match will work over a wide range of
frequencies. I hope to work a number of bands using
the same loop.

My question is -- when I'm ready to test the antenna
do I adjust the gamma match at the lowest frequency I
plan to use, or the highest?

I have considered other forms of coupling the
rig to the transmitter but prefer to use the gamma
match.

Thanks in advance for any assistance or advice in this
matter.

Irv VE6BP
The US Coast Guard has used circular loop antennas for transmitting. I
remember noting them when I did EMI inspections on several Coast Guard
cutters in the 1990's. Perhaps that knowledge will lead you in the
direction of existing documentation on the methods they used. All of my
data is long gone but I did see this guy's page on-line:

http://www.aa5tb.com/loop.html

Good luck.

Gamma Matching Question
 

On 9/21/2013 12:50 PM, Irv Finkleman wrote:
I am planning to build a magnetic loop antenna and
feed it by means of a gamma match. I understand
that a gamma match will work over a wide range of
frequencies. I hope to work a number of bands using
the same loop.

My question is -- when I'm ready to test the antenna
do I adjust the gamma match at the lowest frequency I
plan to use, or the highest?

I have considered other forms of coupling the
rig to the transmitter but prefer to use the gamma
match.

Thanks in advance for any assistance or advice in this
matter.

Irv VE6BP

Hi, Irv -

See if this link is of any help to you...

http://www.vk1od.net/antenna/GammaMatch/gbs.htm

John KD5YI